Cooker hood and oil fired boiler

swagman

Can anyone advise about the safety of having a recirculating cooker hood over an electric cooker in a kitchen which also has an oil fired central heating boiler?

The kitchen is not huge, about 45 cubic metres, and I'm concerned that carbon monoxide could be drawn into the room.

Canucklehead

Hi

Do you have a conventional flue or balanced?

Conventional.... large 4" or 5" pipe from top of boiler going into chimney or outside up to roof level.

Balanced... straight out through wall with wire cage outside..

Corgi Guy.

swagman

It is a conventional flue.

I came across one website which said that if you have a conventional flue you must NOT duct to outside, but you can have a recirculating cooker hood.

Is that correct? Thanks for your reply.

Canucklehead

Hi

You could have an extractor to outside but you would need to size your air vents from outside to balance the air drawn out by the extractor,PLUS the needs of the boiler.
You could end up with a huge vent which defeats the point of central heating!
So, go with recirculating but it would be worth getting your oil service man/woman in to make sure it doesn't affect the boiler ,again it's all down to the sizeing of fresh air vents. All vents should be directly to outside air.
Even ceiling fans can have an effect on flues.
Corgi Guy.

swagman

Right, I get it thanks. The oil fired boiler is sited on what was the hearth of an open fire, now sealed to form an alcove.

In the chimney breast above is an air vent which leads into the old chimney. The chimney is not sealed, only topped with an air vented ceramic to stop rain and crows. The air vent aperture is about 7" square and covered with a mesh grill.

I will ask our friendly boiler engineer as you suggest, but I get the feeling it sounds ok.

Canucklehead

Hi

Something doesn't sound right .
Are you saying the flue from the boiler doesn't go up the chimney?
Fresh air for boiler should come from vent in wall at low level usually.

Corgi Guy.

swagman

Hi

The flue from the boiler takes a 90% turn and exits through the exterior wall a few inches above the top of the boiler. Outside is the termination of the duct with a wind baffle and a metal grill over it. The pipe to exterior is some 5" in diameter.

The old chimney is not used except for the air vent already mentioned. The room above still has a fireplace in it, never used.

There is no low level air vent, but this is an old house and so there are plenty of 'accidental' air vents, and the kitchen floor is suspended over a 2 foot drop, which itself has plenty of air vents into it.

Canucklehead

Hi

From a gas point of view your boiler would not meet regs.

Flue should rise a min of 4' (1.2m) from the top of the boiler and then a max of 45 degree bend to out side then up to and over roof level to give 600mm free air space around the terminal.
Do you have the installation book? If not then maybe google the make and model and get one . Then you can check the requirements .

Corgi Guy.

swagman

Found them from 18 years ago!
The boiler is a Trianco TRO pressure jet oil fired, and the installation instructions do specify a low level air inlet of 180 sq cm minimum, plus the high level ventilation (we have that). So the installer did not do the low level bit.
The boiler has a Trianco terminal-silencer flue kit which "dispenses with the need for a conventional chimney". The boiler and flue system "operate under positive pressure". The flue kit in use and shown in the installation leaflet, does have a right angle bend just above the boiler, despite the boiler instructions saying it shouldn't!

So I think I'd better put in a low level air inlet, unless anything in the above rules out the need for it.